This is a growing term throughout the heartland of the United States believed to have been started by some misinterpretation of a popular rap artist's music. " 'ngyangyow" --appropriately begun with one apostrophe, as there are no other words in english (that I am aware of) which begin with the phoneme represented with 'ng'...
It could be a noun, verb, adjective, or explative... definitely used contextually... It's almost like a cross between the exaggerated teenage angst-ridden "I KNOW..." and the genuine educated yet somewhat sarcastic adults "Thank-you~" -- yet with a slight twist... It somehow got breeded with the term "Whatever!" and now resides in the bowels of Urban Dictionary, of all places. There's only one thing to say about this, you guessed it!! "NGYANGYOW!!!

Pronounced like "ying-yang" without the "yi" at the beginning of the word hence the apostrtophe (') beginning the word as not many words in the english language start with the "ng" sound. The last syllable is just "yow".

1 "Man, that guy's just full of 'ngyangyow!"
2 "man, that guy is such a 'ngyangyow!"
3 Jack:"Dum-de-dumm blah blah... I'm a butt-sniffing circus bear." Buddy:"...'ngyangyow."

As an exclamation, it is also quite handy/appropriate when walking around someone just standing in public for no apparent reason. Like a person (who gives an impression they most likely don't understand the local language very well) at your grocery store, half blocking the entrance/exit. When you walk around them instead of saying "excuse me!", you give an understanding nod and say "...'ngyangyow."